She listened live as Col. Steven McCraw, director of the Texas Department of Public Safety, told dozens of reporters and millions of viewers watching live that a "teacher" had propped the door open with a rock, allowing the shooter to enter the school through a door that was supposed to lock automatically.DPS officials declined to respond to questions for this report about the origin of the mistake and have referred ABC News to the agency's prior statements and apology.In a previous statement to ABC News, DPS spokesman Travis Considine explained: "At the outset of the investigation, DPS reported that an unnamed teacher at Robb Elementary School used a rock to prop open the door that the shooter used to enter the school building.Gutierrez told the commission that the explanation of a simple mistake was unconvincing and hard to believe because, in the first days after the school shooting, he said he personally watched as a team of DPS investigators reviewed surveillance camera footage closely."When they accused Amy Marin, they knew that she absolutely did the right thing and yet they let her feel the pain of that accusation for five days, and she will never be the same.""